There is known an ink circulation device for a circulation-type inkjet head corresponding to various kinds of ink, such as solvent ink, oil-based ink or water-based ink. In order to eject a proper liquid drop amount of the ink from the inkjet head, in some cases, the ink is heated to adjust the viscosity thereof.
The shape forming the appearance of the ink circulation device is constituted by a casing. If the ink inside the ink circulation device is heated with a heater mounted on the outer surface of the casing, as the casing is relatively thick, it is difficult to transmit heat generated by the heater to the ink, and there is a problem that the ink cannot be heated to a desired temperature.